《计算机专业英语》课件003

PartThreeDatabaseManagementSystemPassageADatabaseBasics

PassageBStructuredQueryLanguage(SQL)

PassageCMicrosoftSQLServer

PassageDOracleDatabase

ReadingMaterialMicrosoftAccess2007

PassageADatabaseBasicsThedatabaseisnowsuchanintegralpartofourday-to-daylifethatoftenwearenotawareweareusingone.Ourentireworldisbasedoninformation.Thetelephonebook,thescheduleofasportsteam,andauniversity’stimetablearealldifferenttypesofdatabases.Theytakeinformationandorganizeitinsuchawaythatwecanextractanyinformationthatwedesireandactuponthatinformation.Somedatabasesaresimple,suchasaphonelist;otherdatabasesaresolargeandcomplex,theyneedcomputerspacegreaterthan100PC’scombined.Databasescansimplifyourworkandourlivesbykeepingusorganized.1. WhatisaDatabase?Databasesaredesignedtoofferanorganizedmechanismforstoring,managingandretrievinginformation (检索信息).[1]Theydosothroughtheuseoftables.Ifyou’refamiliarwithspreadsheets (电子数据表)likeMicrosoftExcel,you’reprobablyalreadyaccustomedtostoringdataintabularform (表格形式).It’snotmuchofastretchtomaketheleapfromspreadsheetstodatabases.TablesJustlikeExceltables,databasetablesconsistofcolumns (列)androws (行).Eachcolumncontainsadifferenttypeofattribute (属性)andeachrowcorrespondstoasinglerecord (记录).Forexample,imaginethatwewerebuildingadatabasetablethatcontainednamesandtelephonenumbers.We’dprobablysetupcolumnsnamed“ID”,“FirstName”,“LastName”and“Telephone”,thenwe’dsimplystartaddingrowsunderneaththosecolumnsthatcontainedthedatawe’replanningtostore,ifwehave50employees,we’dwindupwithatablethatcontains50rows.Figure3-1isasampleoftable.DatabaseADatabaseincludesometables,andyou’reabletomanipulate (操作)data:Retrieveallrecordsthatmatchcertaincriteria,Updaterecordsinbulk,Cross-referencerecordsindifferenttables,Performcomplexaggregatecalculations.YoucanseeFigure3-2.Figure3-1SampleoftableFigure3-2DatabaseandtablesDBMS(DatabaseManagementSystem,数据库管理系统)Asoftwaresystemthatenablesuserstodefine,create,maintain,andcontrolaccesstothedatabase.TheDBMSisthesoftwarethatinteractswiththeusers’applicationprogramsandthedatabase.Figure3-2alsoshows.DatabaseKeys

 KeyAdatabasekeyisanattributeutilizedtosortand/oridentify (确定)datainsomemanner.Eachtablehasaprimarykey (主键)whichuniquely (唯一地)identifiesrecords.Foreignkeys (外键)areutilizedtocross-referencedatabetweenrelationaltables.Figure3-3showsprimarykey.

 PrimaryKeysEverydatabasetableshouldhaveoneormorecolummsdesignatedastheprimarykey.Thevaluethiskeyholdsshouldbeuniqueforeachrecordinthedatabase.Forexample,we’dneedtoselectanappropriateprimarykeythatwoulduniquelyidentifyeachemployee.Onceyoudecideuponaprimarykeyandsetitupinthedatabase,thedatabasemanagementsystemwillenforcetheuniquenessofthekey.[2]Ifyoutrytoinsertarecordintoatablewithaprimarykeythatduplicatesanexistingrecord,theinsertwillfail.Figure3-3Primarykey

 ForeignKeysTheforeignkeysareusedtocreaterelationshipsbetweentables.Naturalrelationshipsexistbetweentablesinmostdatabasestructures.InFigure3-4showstheDepartmentIDcolumnintheEmployeestableisaforeignkeythatreferencestheDepartmentstable.Figure3-4Relationoftwotables2. DatabaseSoftwareOptionsDesktopDatabasesandServerDatabasesDatabaseManagementSystemscanbedividedintotwocategories—desktopdatabasesandserverdatabases(asshowninFigure3-5).Desktopdatabasesareorientedtowardsingle-userapplicationsandresideonstandardpersonalcomputers.Desktopdatabasesofferaninexpensive(便宜),simplesolutiontomanylesscomplexdatastorageandmanipulationrequirements.Top5DesktopDatabasesare:MicrosoftAccess2007,FilemakerPro,AlphaFive(Figure3-6),ParadoxandLotusApproach.Figure3-5TwotypeofdatabaseIBMFigure3-6DesktopdatabasesServerdatabasescontainmechanismstoensurethereliability(可靠性)andconsistency(一致性)ofdataandaregearedtowardmulti-userapplications.[3]Thesedatabasesaredesignedtorunonhigh-performanceserversandcarryacorrespondinglyhigherpricetag (标价).Serverdatabases,suchasMicrosoftSQLServer,OracleandIBMDB2,offerorganizationstheabilitytomanagelargeamountsofdataefficientlyandinamannerthatenablesmanyuserstoaccessandupdatethedatasimultaneously(同时地).Ifyou’reabletocarrytheheftypricetag(负担得起的标价),aserver-baseddatabasecanprovideyouwithacomprehensivedatamanagementsolution(全面的数据管理解决方案).

 Flexibility.Server-baseddatabasescanhandlejustaboutanydatamanagementproblemyoucanthrowatthem.

 Powerfulperformance.Server-baseddatabasesareaspowerfulasyouwantthemtobe.

 Scalability(规模可伸缩性).Serverdatabasesareabletogracefullyhandlearapidlyexpandingamountofusersand/ordata.DefineYourRequirementsIt’simportanttodoacarefulneedsanalysisbeforeyoudiveinandcommittoadatabasesolution.You’lloftenfindthatadesktopdatabaseissuitableforyourbusinessrequirementswhenyouoriginallyplannedtopurchaseanexpensiveserver-basedsolution.[4]KeyWordsandExpressionstable['teibl]n.表格vt.制表column['kɔləm]n.列,专栏,纵队row[rəu]n.行v.划船attribute[ə'tribju(:)t]n.属性;特性,特质record['rekɔ:d]n.记录vi.录音a.创记录的manipulation[mənipju'leiʃən]n.操纵,控制definition[defi'niʃən]n.定义gear[giə]vt.使适应,使适合,调整perform[pə'fɔ:m]vt.执行;完成;做identify[ai'dentifai]vt.确认;识别uniquely[ju(:)‘ni:kli]ad.独特地,唯一地constraint[kən'streint]n.约束;限制primarykey['praiməriki:]主键foreignkey['fɔrinki:]外键scalability[skeilə‘biliti]n.规模可伸缩性,可升级Notes[1] Databasesaredesignedtoofferanorganizedmechanismforstoring,managingandretrievinginformation.设计数据库是为了给存储、管理和检索信息提供一个有组织的机制。[2] Onceyoudecideuponaprimarykeyandsetitupinthedatabase,thedatabasemanagementsystemwillenforcetheuniquenessofthekey.一旦你在数据库中确定了一个主键并进行了设置，数据库管理系统便会强制执行关键字的唯一性。[3] Serverdatabasescontainmechanismstoensurethereliabilityandconsistencyofdataandaregearedtowardmulti-userapplications.服务器数据库包含保证数据可靠性和一致性的机制，并且能适应多用户应用。[4] You’lloftenfindthatadesktopdatabaseissuitableforyourbusinessrequirementswhenyouoriginallyplannedtopurchaseanexpensiveserver-basedsolution.当你计划购买一个昂贵的基于服务器的解决方案时，你经常会发现桌面数据能适合你的业务需求。ExercisesⅠ. Choosethecorrectanswer.

1. Adatabaseis

.a. acollectionoflogicallyrelateddataelementsb. usedtomeetthemultipleprocessingandretrievalneedsc. usedfororganizationsd. notusedforindividuals2. ADBMScanbeusedto

.a. createdatabaserecords b. processdataelementsc. maintaindatabaserecords d. presentdataelements3. Whichisnotconsistedofdatabasetables?

a. attribute b.columns c.rows d.spreadsheets4. Whichonisserverdatabase?

a. MicrosoftAccess b.FoxProc. MicrosoftSQLServer d.ParadoxⅡ. Fillintheblankswithappropriatewordsorphrases.1. DatabaseManagementSystemscanbedividedintotwocategories—_____andserverdatabases.2. _____containmechanismstoensurethereliabilityandconsistencyofdataandaregearedtowardmulti-userapplications.3. Top5DesktopDatabasesare:_____,FilemakerPro,AlphaFive,

_____,LotusApproach.4. Eachtablehasa_____whichuniquelyidentifiesrecords.Ⅲ. WriteTrueorFalseforthefollowingstatementsaccordingtothepassage.1. TherearethreetypeofDatabase:DesktopDatabases,ServerDatabasesandWeb-enabledDatabases.()2. Desktopdatabasesofferanexpensive,simplesolutiontomanylesscomplexdatastorageandmanipulationrequirements.()3. TopublishdatabaseontheInternetmustuseaserverdatabase.()4. Theforeignkeysareusedtocreaterelationshipsbetweentables.()TipsWeb-enabledDatabases：Nowadays,almosteverydatabaseapplicationcallsforsomekindofwebinteraction.Manypeopleassumethatifyou’relookingtopublishyourdatabaseontheInternet,youneedtouseaserverdatabase.That’snotnecessarilytrue—adesktopdatabasecould(inexpensively!)meetyourneeds.PassageBStructuredQueryLanguage(SQL)Mostlarge-scaledatabasesusetheStructuredQueryLanguage(SQL)tofacilitate (方便)userandadministratorinteractions.Thislanguageoffersaflexibleinterfacefordatabasesofallshapesandsizes (所有形式和大小的数据库).[1]

Didyoueverwonderhowtheapplicationswork?TheyuseSQL!Thefront-endtranslatesyourmouseclicksandtextentriesintoSQLandthen“speaks”tothedatabaseintheuniversallanguageofSQL.Figure3-7shows.Figure3-7SQLThefirstimportantpointtomakeisthatalldatabasetransactions (事务处理)aremadeinSQL,whetheryourealizeitornot.Nowadays,therearealargenumberofgraphicaluserinterfacesthatsimplifydatabaseadministrationtasks.Ifyou’reaSQLServeruser,youmaybefamiliarwithtoolslikeEnterpriseManager (企业管理器).[2]1. DDLandDMLSQLcommandscanbedividedintotwomainsublanguages.TheDataDefinitionLanguage(DDL)(数据定义语言)containsthecommandsusedtocreateanddestroydatabasesanddatabaseobjects.AfterthedatabasestructureisdefinedwithDDL,databaseadministratorsanduserscanusetheDataManipulationLanguage(DML)(数据操作语言)toinsert,retrieveandmodifythedatacontainedwithinit.[3]2. DataDefinitionLanguage(DDL)Thesecommandswillprimarilybeusedbydatabaseadministratorsduringthesetupandremovalphasesofadatabaseproject.CREATE,thecommandcanbeusedtoestablishdatabases:Example1CREATEDATABASEcompany_info(Figure3-8)Createanemptydatabasenamed“company_info”onyourDBMS.Afterusingthedatabase,yournextstepistocreatetablesthatwillcontaindata.USE,thecommandallowsyoutospecifythedatabaseyouwishtoworkwithwithinyourDBMS,youcanmanipulationsomecommands.Figure3-8CREATEDATABASEExample2CREATETABLEemployees(idintnotnull,first_namechar(20)notnull,last_namechar(20)notnull)(Figure3-9)Establishe (建立)atabletitled“employees”inthecurrentdatabase.Inthisexample,thetablecontainsthreeattributes:id,first_nameandlast_name.ALTER,thecommandallowsyoutomakechangestothestructureofatablewithoutdeletingandrecreatingit.Figure3-9USEDATABASEandCREATETABLEExample3ALTERTABLEemployeesADDTelephonechar(15),salarymoneynull(Figure3-10)Thisexampleaddsanewattributetotheemployeestable—anemployee’ssalary.The“money”argument (参数)specifies (指明)thatanemployee’ssalarywillbestoredusingadollarsandcentsformat.Finally,the“null”keywordtellsthedatabasethatit’sOKforthisfieldtocontainnovalueforanygivenemployee.Figure3-10ALTERTABLEDROP,itallowsustoremove (移除)entiretableordatabasefromDBMS:Example4DROPemployeesExample5DROPDATABASEcompany_infoNotice!Usethiscommandwithcare!RememberthattheDROPcommandremovesentiredatastructuresfromyourdatabase.Ifyouwanttoremoveindividualrecords,usetheDELETEcommandoftheDataManipulationLanguage.3. DataManipulationLanguage(DML)Thesecommandswillbeusedbyalldatabaseusersduringtheroutineoperationofthedatabase.SELECT,itisthemostcommonlyusedcommandinSQL.Itallowsdatabaseuserstoretrievethespecificinformationtheydesirefromanoperationaldatabase.Example6SELECT*FROMemployeesAlternatively,usersmaywanttolimittheattributesthatareretrievedfromthedatabase.Forexample,youmayrequirealistofthelastnamesofallemployeesinthecompany,suchasFigure3-11.Figure3-11SELECTTheWHEREclausecanbeusedtolimittherecordsthatareretrievedtothosethatmeetspecifiedcriteria.Thefollowingcommandretrievesallofthedatacontainedwithinemployeesforrecordsthathaveasalaryvaluegreaterthan4,500:Example7SELECT*FROMemployeesWHEREsalary>4500INSERT,thecommandinSQLisusedtoaddrecordstoanexistingtable.Example8INSERTINTOemployeesvalues(12,'Bart','Simpson','65123485',4700)Fivevaluesspecifiedforanewemployee’srecordthatcorrespondtothetableattributesweredefined:ID,FirstName,LastName,Telephone,andsalary.UPDATE,thecommandcanbeusedtomodifyinformationcontainedwithinatable,eitherinbulkorindividually(Figure3-12).Thisyear,thecompanygivesallemployeesa10%increaseintheirsalary:Example9UPDATEemployeesSETsalary=salary*1.1DELETE,thecommandwithaWHEREclausecanbeusedtoremovetherecordfromtheemployeestable.Example10DELETEFROMemployeesWHEREemployee_id=12

Figure3-12UPDATEKeyWordsandExpressionsfacilitate[fə'siliteit]vt.帮助,使容易,促进transaction[træn'sækʃən]n.事务,办理establish[is'tæbliʃ]vt.建立,设立argument['ɑ:gjumənt]n.参数，变量specify['spesifai]v.指明,具体说明GraphicalUserInterfaces['græfikəl]['ju:zə]['intə(:)feis](GUIs)图形用户界面EnterpriseManager['entəpraiz]['mænidʒə]企业管理器DataDefinitionLanguage(DDL)数据定义语言DataManipulationLanguage(DML)数据操作语言Notes[1] Mostlarge-scaledatabasesusetheStructuredQueryLanguage(SQL)tofacilitateuserandadministratorinteractions.Thislanguageoffersaflexibleinterfacefordatabasesofallshapesandsizes.多数大规模数据库使用结构化查询语言(SQL)以方便用户和管理者交互，这种语言为所有形式和大小的数据库提供一个灵活的接口。[2] Nowadays,therearealargenumberofgraphicaluserinterfacesthatsimplifydatabaseadministrationtasks.Ifyou’reaSQLServeruser,youmaybefamiliarwithtoolslikeEnterpriseManager.当今，有很多简化数据库管理任务的图形用户界面，如果你是一个SQL服务器的用户，你可能熟悉企业管理器的工具。[3] AfterthedatabasestructureisdefinedwithDDL,databaseadministratorsanduserscanusetheDataManipulationLanguagetoinsert,retrieveandmodifythedatacontainedwithinit.在数据库用DDL定义之后，数据库管理者和用户能够使用数据操作语言(DML)进行插入、检索和修改其中的数据。ExercisesⅠ. Choosethecorrectanswer.1. WhichofthefollowingisDMLcommands?_________a. CREATEb. SELECTc. DROP d. ALTER2. WhichofthefollowingisDDLcommands?_________a. INSERTb. DELETE c. USE d. SELECT3. CREATETABLEdeparment(department_idintnotnull,departmen_namechar(20)notnull,department_chiefchar(20)),thetablecontainsattributesexcept_________.a. deparment b. department_id c. departmen_name d. department_chief4. WhichofthefollowingcommandsCANchangethedataoftable?_________a. USE b. SELECT c. UPDATE d. CREATEⅡ. Fillintheblankswithappropriatewordsorphrases.1.TheDataDefinitionLanguagecontainsthecommandsusedto

anddestroydatabasesanddatabaseobjects.2.DataDefinitionLanguagecontainsCREATE,

,

andDROP.3. TheDataManipulationLanguagecanbeusedtoinsert,retrieveand

thedatacontainedwithinit.4. TheDataManipulationLanguagecontains

,INSERT,

,andDELETE.Ⅲ. TranslatethefollowingsentencesfromEnglishintoChinese.1. ThefirstimportantpointtomakeisthatalldatabasetransactionsaremadeinSQL,whetheryourealizeitornot.2.  Ifyouwanttoremoveindividualrecords,usetheDELETEcommandoftheDataManipulationLanguage.TipsThecorrectpronunciationofSQLisacontentiousissuewithinthedatabasecommunity.IntheirSQLstandard,theAmericanNationalStandardsInstitutedeclaredthattheofficialpronunciationis“esqueueel”.However,manydatabaseprofessionalshavetakentotheslangpronunciation“sequel”.Thechoiceisyours.PassageCMicrosoftSQLServerMicrosoftSQLServerisapowerfulrelationaldatabasemanagementsystemcatering (满足)tohigh-enduserswithadvancedneeds.[1]AlongwithOracle,MicrosoftSQLServeriswidelyregardedasoneofthetwomainfull-featureddatabasesystemsonthemarkettoday.MicrosoftSQLServer2008,code (代号)name“Katmai”,thenextgenerationofSQLServer.YoucanseethecodenameinFigure3-13.Figure3-13MicrosoftSQLServer20081. CentralizedDataServicesAdministrationSQLServerManagementStudio,asshowninFigure3-14,isacomprehensive (全面),centralized (集中)managementtoolthatenablesyoutomanageallofyourSQLServerinstancesthroughasingleinterface.[2]

2. IntegratedConfigurationSQLServerConfigurationManager,asshowninFigure3-15,enablessystemadministratorstomanageSQLServerservicesandnetworklibrariesfromasinglelocation.Figure3-14SQLServerManagementStudioFigure3-15SQLServerConfigurationManager3. ConfiguringSQLServerwithPolicy-basedManagementTheDeclarativeManagementFramework(DMF)providestheabilitytodefinepoliciesthatapplytoservers,databases,andotherobjectsinyourdataenvironment.[3]DMFFacetsEachDMFfacetrepresentsanaspectofSQLServermanagementinwhichoneormorerelatedconfigurationoptionsisdefined.SQLServer2008includesanumberofpredefinedfacets.Forexample,SQLServer2008includestheApplicationRoleFaceAreafacet,asshowninFigure3-16.Figure3-16ApplicationRoleFaceYoucancreateconditionstodefineadesiredconfigurationthatisbasedonthesettingsinafacet,asshowninFigure3-17.Finally,todefineapolicy,yousimplyspecifytheconditionthatyouwanttoenforce,asshowninFigure3-18.SummaryMicrosoftSQLServer2008buildsonthemanagementcapabilitiesofpreviousversionsandprovidesavarietyoftoolsandframeworkstohelpyoumanageyourenterprisedataenvironment.Anewend-to-endperformancemonitoringandanalysissuitehelpsyoutooptimizetheresponsivenessandscalabilityofyourSQLServerservicesacrosstheenterprise,andthescalablemanagementinterfacesandtoolshelpyoutoreduceservermanagementeffortandfocusonhighervalueactivities.Figure3-17DefineconditionFigure3-18DefineapolicyKeyWordsandExpressionscater['keitə]v.满足,迎合,承办伙食releases[ri'li:s]n.版本,发布comprehensive[kɔmpri'hensiv]a.全面的,广泛的,有理解力的centralized[sentrəlaizd]a.集中的,中央集权的ConfigurationManager[kənfigju'reiʃən]['mænidʒə]配置管理器Policy-basedManagement['pɔlisibeist]['mænidʒmənt]

基于策略管理DeclarativeManagementFramework(DMF)[di'klærətiv'mænidʒmənt'freimwə:k]

声明式管理框架Notes[1] MicrosoftSQLServerisapowerfulrelationaldatabasemanagementsystemcateringtohigh-enduserswithadvancedneeds.微软的SQL服务器是一个满足高端用户高级需求的强有力的关系数据库管理系统。[2] SQLServerManagementStudioisacomprehensive,centralizedmanagementtoolthatenablesyoutomanageallofyourSQLServerinstancesthroughasingleinterface.SQLServerManagementStudio是一个通过单一界面让你管理所有SQL服务器实例的全面集中的管理工具。[3] TheDeclarativeManagementFramework(DMF)providestheabilitytodefinepoliciesthatapplytoservers,databases,andotherobjectsinyourdataenvironment.声明式管理框架(DMF)提供应用于服务器、数据库和数据环境中其他对象的定义策略的能力。ExercisesⅠ. Fillintheblankswithappropriatewordsorphrases.1.AlongwithOracle,Microsoft

iswidelyregardedasoneofthetwomainfull-featureddatabasesystemsonthemarkettoday.2.SQLServerManagementStudioenablesyoutomanageallofyourSQLServer 

 throughasingleinterface.3.TheDeclarativeManagementFrameworkprovidestheabilitytodefinepoliciesthatapplytoservers,

,andotherobjectsinyourdataenvironment.Ⅱ. Writetrueorfalseforthefollowingstatementsaccordingtothepassage.

1. MicrosoftSQLServerisapowerfulnetlikedatabasemanagementsystem.()2. MicrosoftSQLServer2008,codename“Katmai”,whichincludesanumberofpredefinedfacets.()3. Basedonthesettingsinafacetyoucancreateconditionstodefineadesiredconfiguration.()4.SQLServerConfigurationManagerenablessystemadministratorstomanageSQLServerservicesandnetworklibrariesfromasinglelocation.()Ⅲ. TranslatethefollowingsentencesfromEnglishintoChinese.

1.MicrosoftSQLServer2008buildsonthemanagementcapabilitiesofpreviousversionsandprovidesavarietyoftoolsandframeworkstohelpyoumanageyourenterprisedataenvironment.2.EachDMFfacetrepresentsanaspectofSQLServermanagementinwhichoneormorerelatedconfigurationoptionsisdefined.SQLServer2008includesanumberofpredefinedfacets.TipsSQLServerStoredProceduresMicrosoftSQLServerprovidesthestoredproceduremechanism(Figure3-19)tosimplifythedatabasedevelopmentprocessbygroupingTransact-SQLstatementsintomanageableblocks.BenefitsofStoredProcedures:Precompiledexecution,Reducedclient/servertraffic,Efficientreuseofcodeandprogrammingabstraction,Enhancedsecuritycontrols.Figure3-19SQLServerStoredProceduresPassageDOracleDatabaseTheOracledatabaseisthemarket-leader (市场领袖)andthepreferreddatabaseforhundredsofthousandsofenterprisesaswellasapplicationdevelopersanddatabaseadministratorsworldwide.[1]Overtheyears,enterpriseshavecometorelyontheOracledatabasetoprovideunparalleled (无比的)performance (性能)andreliability (可靠性).Oraclehasundergonemanyrevisionssinceitsfirstreleaseinthelate1970s,butin1997Oracle8wasreleasewithextendedobject-relationcapabilities,andimprovedperformanceandscalabilityfeatures.In1999,Oracle8iwasreleasedaddedfunctionalitysupportingInternetdeploymentandin2001Oracle9iwasreleasedwithadditionalfunctionalityaimedatthee-Businessenvironments (电子商务环境).[2]Whilethe“i”standsfor“Internet”,the“g”intheOracle10gstandsfor“grid”,theproductlinestargetsgridcomputing.In2007Oracle11gwasreleased.WhatisAnOracleDatabase?Basically,therearetwomaincomponentsofOracledatabase––instanceanddatabaseitself.Aninstanceconsistsofsomememorystructuresandthebackgroundprocesses (后台处理),whereasadatabasereferstothediskresources.[3]Figure3-20willshowyoutherelationship.Figure3-20TwomaincomponentsofOracle1. InstanceThememorystructuresandbackgroundprocessesconstituteaninstance.ThememorystructureitselfconsistsofSystemGlobalArea(SGA)(系统全局区),ProgramGlobalArea(PGA)(程序全局区),andanoptionalarea–SoftwareAreaCode.Ontheotherhand,themandatory (托管的)backgroundprocessesareDatabaseWriter(DBWR),LogWriter(LGWR),Checkpoint(CKPT),SystemMonitor(SMON),andProcessMonitor(PMON).AndanotheroptionalbackgroundprocessesareArchiver(ARCn),Recoverer(RECO),etc.Figure3-21willillustratetherelationshipforthosecomponentsonaninstance.Figure3-21Theinstancecomponents2. DatabaseThedatabasereferstodiskresources(资源),andisbrokenintotwomainstructures—LogicalstructuresandPhysicalstructures(asshowninFigure3-22).LogicalStructuresOracledatabaseisdividedintosmallerlogicalunitstomanage,storeandretrievedataefficiently.Thelogicalunitsaretablespace,segment,extentanddatablock.PhysicalStructuresThephysicalstructuresarestructuresofanOracledatabase(inthiscasethediskfiles)thatarenotdirectlymanipulatedbyusers.Thephysicalstructureconsistsofdatafiles,redologfiles,andcontrolfiles.Figure3-22DatabasestructureKeyWordsandExpressionsunparalleled[ʌn'pærəleld]a.无比的,优良无比的,空前的performance[pə'fɔ:məns]n.性能,特性reliability[rilaiə'biliti]n.可信度,可靠性mandatory['mændətəri]a.命令的,托管的resource[ri'sɔ:s]n.资源,财力;消遣,娱乐e-Businessenvironment[i:'biznis][in'vairənmənt]电子商务环境backgroundprocesses['bækgraund]['prɔses]后台处理Notes[1] TheOracledatabaseisthemarket-leaderandthepreferreddatabaseforhundredsofthousandsofenterprisesaswellasapplicationdevelopersanddatabaseadministratorsworldwide.Oracle数据库是数据库的市场领袖，不仅是全世界的应用开发者和数据库管理者，也是成千上万企业的首选数据库。[2] In1999,Oracle8iwasreleasedaddedfunctionalitysupportingInternetdeploymentandin2001Oracle9iwasreleasedwithadditionalfunctionalityaimedatthee-Businessenvironments.1999年发布的Oracle8i增加了支持因特网布署的功能，2001年发布的Oracle9i增加了电子商务环境的附加功能。[3] Aninstanceconsistsofsomememorystructuresandthebackgroundprocesses,whereasadatabasereferstothediskresources.实例由一些存储结构和后台处理组成，而数据库指磁盘资源。ExercisesⅠ. Choosethecorrectanswer.1. Oracledatabasehastwomaincomponents––Databaseand

.a.SystemGlobalArea b.SystemMonitorc.Instance d.ProgramGlobalArea2. Thememorystructureitselfconsistsoffollowingexcept

.a.SystemGlobalArea b.DatabaseWriterc.ProgramGlobalArea d.SoftwareAreaCode3. Whichofthefollowingisoneofthelogicalunit?

a.tablespace b.datafilesc.redologfiles d.controlfiles4. Thephysicalstructureconsistspartsexcept

.a.datafiles b.redologfilesc.controlfiles d.datablockⅡ. Fillintheblankswithappropriatewordsorphrases.1. Aninstanceconsistsofsome

andthebackgroundprocesses.2. TheOracle’sdatabaseisbrokenintotwomains